Urinalysis in Pyonephrosis: Does a Normal Result Rule Out Pyonephrosis?

Research Article

Austin J Radiol. 2015;2(5): 1030.

Urinalysis in Pyonephrosis: Does a Normal Result Rule Out Pyonephrosis?

Mougnyan Cox¹*, Ifechi Momah², Huan Dong¹ and Santosh Selvarajan¹

¹Radiology Resident, Thomas Jefferson University, USA

²Radiology Resident, Georgetown University, USA

*Corresponding author: Mougnyan Cox, Radiology Resident, Thomas Jefferson University, 132 South 10th Street, Philadelphia, PA 19107, USA

Received: July 20, 2015; Accepted: August 14, 2015; Published: August 18, 2015


Purpose: To determine if a normal preprocedural urinalysis rules out Pyonephrosis.

Methods: Urinalysis results, white cell count, and bandemia obtained within 24 hours of subsequent percutaneous nephrostomy were reviewed in patients with documented Pyonephrosis.

Results: 26 out of 27 patients with Pyonephrosis had an abnormal urinalysis. One patient with Pyonephrosis had a negative urinalysis and subsequently grew Candida albicaans on urine cultures.

Conclusion: A normal preprocedural urinalysis does not rule out Pyonephrosis.

Keywords: Nephrostomy; Percutaneous; Pyonephrosis; Urinalysis


Pyonephrosis is a medical emergency, and is defined as the presence of pus in an obstructed renal collecting system [1]. Patients usually present with fever, flank pain, leukocytosis, and an abnormal urinalysis [2]. Patients with proven Pyonephrosis may be a febrile [2], and ultrasound was only 62% sensitive for detecting Pyonephrosis in one study with some patients have frank pus on urine aspiration despite an anechoic renal collecting system [3]. Due to the high morbidity and mortality associated with Pyonephrosis, intravenous administration of broad-spectrum antibiotics and prompt urinary drainage is indicated whenever the diagnosis is suspected [2,4]. While it is known that patients with Pyonephrosis may not always present with fever or an elevated white count, it is less clear whether a normal Urinalysis (UA) in a patient with a dilated renal collecting system rules out the presence of Pyonephrosis. The purpose of our study was to determine the sensitivity of a preprocedural urinalysis for aspiration-proved Pyonephrosis.


After Institutional Review Board approval was obtained, a retrospective review of an imaging database and clinical charts from 2006-2014 was performed. Patients were selected on the basis of percutaneous aspiration procedure results specifying the presence of pus at the time of aspiration. The clinical charts of these patients were also reviewed for relevant clinical history as well as inflammatory markers (leukocytosis, bandemia) and results of preprocedural urinalysis performed up to 24 hours prior to aspiration.

All Percutaneous urinary interventions were performed by 5 fellowship-trained interventional radiologists with 60 years of cumulative experience. The results of urine cultures from samples obtained at the time of aspiration were recorded when available.


Thirty patients were found to have Pyonephrosis, confirmed by aspiration of grossly purulent urine at the time of Percutaneous Nephrostomy (PCN). There were 23 female and 7 male patients. The average age of the patients was 58, with a range of 23 to 96 years. Renal stones were implicated as the cause of Pyonephrosis in 16 out of 30 patients (53%). An additional 10 patients had Pyonephrosis in the setting of a pelvic malignancy (33%), most commonly cervical cancer, present in four patients. There was a notably high rate of paraplegia/tetraplegia (5 out of 30 cases or 17%) in our patients with Pyonephrosis. This may be Multifactorial, with bladder dysfunction and frequent access of the urinary collecting system contributing to various degrees. Two patients had a pregnancy complicated by Pyonephrosis, and were in their second trimester at the time of intervention (Figure 1&2).